Example embodiments relate to a semiconductor device and a method of manufacturing a semiconductor device. More particularly, example embodiments relate to a semiconductor device including an electrode structure and a method of manufacturing a semiconductor device having an electrode structure.
A semiconductor memory device usually includes a transistor such as a metal oxide semiconductor (MOS) transistor for a switching element. The transistor in a semiconductor memory device includes a gate electrode having a relatively low resistance and a proper work function in accordance with the electrical characteristics of the transistor.
As for a conventional semiconductor memory device, a gate electrode of a transistor generally includes polysilicon having a work function adjusted by impurities doped therein. Further, the gate electrode may include a metal layer to reduce a resistance thereof. However, the impurities in the gate electrode may be diffused in successive processes for manufacturing the conventional semiconductor memory device, so that the transistor may not ensure desired threshold voltage and electrical characteristics. Additionally, the metal layer in the gate electrode may cause the contamination of other elements in the semiconductor device in subsequent heat treatment process and/or a wet etching process.